His summon can 1-shot your weaker party members so I moved my ranged units out of sight when talking to him, then walked them into combat after starting the fight. If you move them in right after the dog summons his bone crusher then the bone crusher will have been summoned by your melee units but he will then run at your weak units and waste a turn. Healing spells are really good here because they are both undead.

If anyone play in solo and struggle with fight against the Andras (and his troll, worm and two skeletons that he summons), heres how I did this (Honour difficulty, solo challenge)

1. First talk to the dog, make him summon troll and flee from the fight (Escapist talent is very useful here but not a must - anyway remember about an option to respec on Lady Vengeance).2. Before the fight use some movement buffs (like Haste). You can also use some slow on the ground between you and enemies (and troll already standing next to him) like Ice or Oil.3. Start the fight by using some aoe attack from over the max range (like Laser Ray or Winter Blast for example). You can also stand even further and summon something (for example a cat) in the range of agro, but why refuse to deal some nice dmg to his magic armor with free action cost? ^_^"4. Move to the place where is the fight against four dead heroes (elf, lizard, dwarf and human). Use the ladder to get the high ground. You might need some summon active to hold the combat for you (because of the distance). Up here you are safe from troll and if you stick to the back of platform, skeletons wont be a problem aswell. When dog summon a worm you can either kill him with fire or use teleport to throw down - 2nd option is better to be saved for skeletons.5. Stay up there and kill the dog without problems with his minions, they will vanish once you take down their master (Andras that is).